7 Nov
2007
7 Nov
'07
10:04 p.m.
On Nov 7, 2007, at 7:17 PM, Tony Duell wrote:
This may be a UK .vs. US language difference, but to me :
A 'filament' is a thin wire, heated electircally. A heater (in a
valve)
is a particular type of filament
A filament that's also the cathode (as here) is a 'directly heated
cathode'
A filament that heats a separate cathode is called a 'heater'. The
result
is caleld an 'indirectly heated cathode'
This is the way I learned it, and I'm in the US.
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
[...] the two wires that are a filliment (heater to
some).
As I understand it, a filament and heater are not just two different
words for the same thing (for a long time I thought they were...).
A filament is what this is: the electron emitter is the same thing
that
is generating the heat through ohmic losses. A heater is a case
where
the heat generator is not the same thing that is emitting
electrons, as
in many vacuum tubes: the heater generates heat, which then warms up
the (separate) cathode electrode.